Electronic Structure and Bonding in Tricoordinate Amido Complexes of Transition Metals

Abstract

A theoretical study of bonding and structure in tricoordinate amido complexes with different d n electron configurations is presented. The relative stability of the high- and low-spin states of [Co(NH2)3] is discussed, and the preferred orientation of the amido ligands relative to the coordination plane is analyzed for the high-spin state of the [M(NR2)3] compounds, where M = V(IV), Cr(III), Mn(III), Fe(III), Co(III), or Ni(II) and R = H or SiH3. Comparison of the computational results with experimental data provides information on the influence of electronic and steric effects. The existence of metal−ligand π bonding is discussed in the context of the electron configurations, calculated bond distances, and spin-density distributions.

Structure of Triamidoaluminum Complexes: A Theoretical ab Initio/IMOMM Study

“…We have shown by theoretical calculations that this surprising geometry results from a balance between electronic and steric effects . Analogous conclusions have been reached by Alvarez and co-workers in a recent study of inorganic species, M(NR 2 ) 3 (M = V ... Ni; R = H or SiH 3 ) . In these systems, the orientations of the amido groups again depend on a combination of steric and electronic effects.…”

Receptor versus Counterion: Capability of N,N′‐Bis(2‐aminobenzyl)‐diazacrowns for Giving Endo‐ and/or Exocyclic Coordination of ZnII

“…Full geometry optimisations of the [Zn(L 1 )] 2+ , [Zn(L 2 )] 2+ and [Zn(L 2 )(NO 3 ) 2 ] systems were performed in vacuo by using the standard 6‐31G(d) basis on the ligand atoms and Ahlrichs' valence triple‐ζ (VTC) on Zn 22. The latter basis has been shown to provide accurate molecular structures for several first‐row transition‐metal complexes 23…”

(THF)3LiCl as a Ligand for Low-Coordinate Fe(II): Crystal Structure of [(Me3Si)2N]2Fe(μ-Cl)Li(THF)3

“…5 The common view that bis(triorganosilyl)amido ligands act predominantly as uninegative two-electron σ-bonding ligands toward low-coordinate transition metal centers, exhibiting almost negligible M-N π-bonding, 5b,6 is currently under revision. 7 In any case, the extent of M-N π-bonding is expected to be next to nothing for borylamido complexes, since the nitrogen lone pair engages in strong B-N π-bonding. 8 The iron(II) analogue of Fe[N(SiMe 3 ) 2 ] 3 is Fe[N(SiMe 3 ) 2 ] 2 , which was prepared by metathesis of FeBr 2 (THF) 2 with lithium bis(trimethylsilyl)amide in diethyl ether.…”

“…Since then, bulky amido ligands have been utilized more extensively than any other type of ligand for the stabilization of coordinatively and electronically unsaturated transition metal complexes . The common view that bis(triorganosilyl)amido ligands act predominantly as uninegative two-electron σ-bonding ligands toward low-coordinate transition metal centers, exhibiting almost negligible M−N π-bonding, 5b, is currently under revision . In any case, the extent of M−N π-bonding is expected to be next to nothing for borylamido complexes, since the nitrogen lone pair engages in strong B−N π-bonding …”